The reduction in dental caries over the past 30+ years has been remarkable and started largely with the introduction of fluoride to the water supply. Increased access to dental care, improved oral hygiene, fluoride incorporation into professional dental products and fluoridated toothpaste have also aided in this decline in tooth decay. Unfortunately, dental caries remains a substantial problem for children and adults, particularly in disadvantaged populations. Two NIH-sponsored workshops have expressed concern over the changing patterns of systemic fluoride exposures and noted an increase in the prevalence and severity of dental fluorosis. Therefore, it is extremely important to monitor the intake of fluoride in children in order to help scientists and policymakers to make better informed decisions about the best ways to balance dental caries prevention versus dental fluorosis risk. A major obstacle in the study of fluorosis with various levels of fluoride intake is the absence of an accurate and practical method for measuring combined fluoride intake, both cross-sectionally and cumulatively. We believe that the dentin fluoride levels found in exfoliated primary second molars can serve as an accurate and useful biomarker to monitor cumulative systemic fluoride exposures during infancy and childhood. The main hypothesis of this grant is that the dentin fluoride of exfoliated primary second molars is a good measure of the cumulative fluoride intake. Collected and stored exfoliated primary 2nd molars from the Iowa Fluoride Study (IFS) available to use in this study are a unique set of exfoliated teeth which are to be coupled with detailed, longitudinal fluoride intake data previously collected. Thus, accurate measures of fluoride intake can be matched with dentin fluoride values of the exfoliated teeth of the IFS participants. Preliminary studies have shown that use of an acid digestion and micro-diffusion methodology are suitable techniques to measure dentin fluoride. The primary aims of this application are to determine dentin fluoride levels and assess the strength of the relationships between dentin fluoride levels and fluoride intake from birth to about age nine. Secondarily, these data will also be looked at in terms of the strength of the relationships with fluorosis in the early-erupting and late-erupting permanent teeth. Finally, we will assess the strength of the relationships between dentin fluoride and caries in the early-erupting and late-erupting permanent teeth. Thus, this study will comprehensively assess the utility of dentin fluoride as a biomarker for cumulative childhood fluoride intake, including relationships with fluorosis and caries. PUBLIC HEALTH RELEVANCE: This project is significant in that it can provide a foundation on which policy makers can balance strategies for dental caries prevention through fluoride use with the risks of dental fluorosis by using dentin fluoride levels as a biomarker for cumulative childhood fluoride intake.